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Please prove or disprove that, for symmetric matrix $A=A^T$, we have
$$ \max_x x^T A x \geq Tr(A) $$ where $x = x_1, x_2, ..., x_n]^T \in \mathbb{R}^n$, $x_i \in \{+1, -1\}, i = 1, ..., n$.$$\max_{x \in \{\pm 1\}^n} x^T A x \geq \mbox{Tr}(A)$$
$$ \max_x x^T A x \geq Tr(A) $$ where $x = x_1, x_2, ..., x_n]^T \in \mathbb{R}^n$, $x_i \in \{+1, -1\}, i = 1, ..., n$.
$$\max_{x \in \{\pm 1\}^n} x^T A x \geq \mbox{Tr}(A)$$